I don't know about about Oracle, but it sounds like they were trying to force him to leave to save money. For $175K per year, Oracle could hire more new people with bachelors and/or graduate degrees. Plus, they could also save money on benefits. Long-time employees tend to have more/better benefits that cost the company more. Also, younger employees are less likely to have health issue that force the company to pay for sick-time (or, possibly, more expensive health insurances plans)
Also, some (all?) states force employers to pay higher taxes to cover unemployment benefits if they have a history of firing a lot of people. That may be part of the reason why your BIL was being "encouraged" to quit before they actually fired him.
But don't overlook one possibility. It is possible your BIL screwed up. If he did something wrong, he probably wouldn't volunteer that information to his sister in law. Don't take that personally... it just isn't something you would need to know.
However, in the circumstances you described, I suspect it was just business. He cost that company a lot of money and the management decide they could save money by getting rid of him and others on his team. I hope things work out for him and his family.